Incident Overview
On January 14, 2016, during an approach to Poznań Airport (EPPO), the crew of a Boeing B737-400 selected the landing gear lever to DOWN. The left main landing gear did not indicate it was down and locked. The captain decided to have the first officer move the gear lever to UP and then back to DOWN. After the fourth cycle, the left main gear indicated down and locked, matching the other gears.
Post-Flight Maintenance
After landing and taxiing to the parking position, the captain notified the maintenance control center and made an entry in the technical log. Technical personnel performed a retraction/extension test, suspecting a faulty DOWN position sensor. The test was successful. Subsequently, the logic card was replaced, and the test was again successful. Further checks revealed improper operation of the left main landing gear actuator.
Corrective Action
On January 20, 2016, the left main landing gear actuator was replaced. The aircraft was cleared for further service, and the malfunction did not recur in subsequent flights.
Cause
The cause of the incident was the improper operation of the left main landing gear actuator.